During prior art parallel feed network antenna manufacturing processes, conventional manufacturing tolerances cause the power level at antenna patches to be non uniform. This non uniformity results in the antenna feeding unequal amounts of energy to the patch antennas. Unequally feeding patch antennas results in a ripple in the antenna's overall pattern, thereby causing the performance of the antenna to be non uniform.
Conventional parallel feed network antenna contain numerous parts. Because of the high number of parts that must be manufactured and assembled, antenna manufacture is time consuming and costly.
A typical prior art parallel feed network antenna would include a flat dielectric controlled material such as a circuit board over which a strip of conductive material such as copper has been disposed. The reverse side of the dielectric is also covered with a conductive surface forming what is commonly known as a ground plane. The strip of copper is then either bonded, screwed, or clipped to the dielectric controlled material. The circuit board or dielectric controlled material would then be attached to a cylindrical housing. The attachment mechanism is typically a number of screws or clips. Patches are then attached to the endpoints of the copper strips using either screws or clips. Prior art processes commonly use flat surfaces for forming parallel feed circuits to assure that the resulting antenna will have a consistent relationship between the parallel feed network and the ground plane underneath the parallel feed network.
In conventional parallel feed network manufacturing processes, the parallel feed network is formed over the dielectric controlled material by placing a masking tool over the piece onto which parallel feed network is to be formed. Then, a catalyst is sprayed onto the piece. Next, the mask is removed and a layer of conductive material such as copper is applied over the piece to form a conductive path or strip. Often, the use of the mask to deposit conductive layer(s) onto the dielectric controlled material results in wicking under the edges of the mask and creeping of the deposited conductive material into crevices in the piece. Additional process steps such as trimming are often necessary to remove unwanted material and control the tolerance of the resulting part. However, the trimming process itself results in additional deviations from the desired dimensions.
Other methods include the use of etchbacks to define the conductive strips of the network as well as chemical etching and photo etch processes. However, each of the process steps of these prior art methods affects the tolerance of the part. Prior art methods typically achieve tolerances of between .+-.0.005 to .+-.0.010 inches.
In order to manufacture a parallel feed network antenna having a power output with a uniform pattern, it is critical that the amount of power reaching each patch antenna be equal. Since the power level is a function of the resistance of the conductive strip, and since the resistance of the conductive strip is a function of the length and width of the conductive strip, the tolerances of the manufacture of the copper strip determine whether an equal amount of power is received at each patch antenna.
Thus, the need has arisen for an improved antenna and a method for manufacturing an improved antenna which has improved uniformity of transmission and improved reliability. More specifically, there is need for a parallel feed network which has uniform strips of the parallel feed network and which has fewer parts and which is easier and cheaper to manufacture.